Are solar panel set ups becoming more mainstream?

[hdossett]

Originally Posted by Ramblin

Please post a link to these batteries...

If you want to go direct and DIY, here is a Manufacture's site. I know nothing about it as I have just started looking into (dreaming about) this!

They also have BMSs, and again, I know nothing!

Balqon - Advanced Transportation Solution

H

[jasright]

I'm looking at 100watt panels on amazon. I figure at $180. Each I'll buy about four at a time. I'll eventually have two rows of 16 down the roof of my twentynine foot mh.That would give me 3200 watts of solar power. Plus I'd buy one lifepo4 100ah battery every other month for about $1k. I figure on my budget maybe three years to builf the battery bank I want but it'll last longer than the rv or me. Ill be boonfocking anywhere I want without power hookups. I can hardly wait.

[Ramblin]

Originally Posted by hdossett

If you want to go direct and DIY, here is a Manufacture's site. I know nothing about it as I have just started looking into (dreaming about) this!

They also have BMSs, and again, I know nothing!

Balqon - Advanced Transportation Solution

H

Thanks.

So, this site has a 12V 40Ah battery for $200. To equal the capacity of a pair of 6V golf car batteries, you'd need 6 of them. 6 of them takes up double the space of a pair of golf car batteries, but weighs 14 lbs less. The lithium batteries have a 5 yr warranty but are only rated for 1750 charge/discharge cycles, which I presume would happen once every day under heavy dry camping use. The Lithium batteries cost $1200, whereas the golf car batteries are $300, not including the interconnect cables.

In this example, I fail to see the advantage of Lithium over lead/acid, even if cost were the same. What am I missing?

[vsheetz]

Originally Posted by jasright

I'm looking at 100watt panels on amazon. I figure at $180. Each I'll buy about four at a time. I'll eventually have two rows of 16 down the roof of my twentynine foot mh.That would give me 3200 watts of solar power. Plus I'd buy one lifepo4 100ah battery every other month for about $1k. I figure on my budget maybe three years to builf the battery bank I want but it'll last longer than the rv or me. Ill be boonfocking anywhere I want without power hookups. I can hardly wait.

With AC units, refrigerator vent, antennas, plumbing vents, etc. you have enough space for 32 panels? Interested to know how you are going to physically accommodate this?

On my 37' coach I currently have six 100w panels, with room for four more should I ever want to, while leaving walk room and minimizing shading. If I eliminated walk room I could fit a few more. But not 32...

And where is the space for the batteries?

[hdossett]

Originally Posted by Ramblin

In this example, I fail to see the advantage of Lithium over lead/acid, even if cost were the same. What am I missing?

And in your example, I agree with you, especially if you can get by with two GCs.

But there is more to it than that and I use a spreadsheet to do the math. As a DIYer, I was looking at replacing six GCs. That 660 AH @12V. Figure 50% DOD, and that gives you 330 usable AHs. In reality, considering you're not going to run your generator for four to six hours for a full charge, or, take advantage of all you roof watts, you are looking at maybe 35%-40% useable AHs for a net of 264 AHs useable.

LFP can go 80% DOD, and nearly top off at full rate of charge, therefore you only need 400 AH total to get there!

The 400AH@3.2 is listed at $420, times four is $1,680 for 320 useable AHs vs. $900 for the GCs. Up front cost still high and there is still the BMC, but over the life, with 3 to 4 time the number of cycles brings the life time cost down considerable...

And that's just the math... other things like weight and maintenance come into play also.

Just saying...

This is too much math for this early in the day!

H

[Ramblin]

Originally Posted by hdossett

And in your example, I agree with you, especially if you can get by with two GCs.

I used 2GC's as my example because it was easy. Larger systems just scale, right? So 4xGCs would be double the numbers. 6xGCs, triple, and so on.

Originally Posted by hdossett

But there is more to it than that and I use a spreadsheet to do the math. As a DIYer, I was looking at replacing six GCs. That 660 AH @12V. Figure 50% DOD, and that gives you 330 usable AHs. In reality, considering you're not going to run your generator for four to six hours for a full charge, or, take advantage of all you roof watts, you are looking at maybe 35%-40% useable AHs for a net of 264 AHs useable.

LFP can go 80% DOD, and nearly top off at full rate of charge, therefore you only need 400 AH total to get there!

The 400AH@3.2 is listed at $420, times four is $1,680 for 320 useable AHs vs. $900 for the GCs. Up front cost still high and there is still the BMC, but over the life, with 3 to 4 time the number of cycles brings the life time cost down considerable...

And that's just the math... other things like weight and maintenance come into play also.

Just saying...

This is too much math for this early in the day!

H

Thanks for that info. I'm still not convinced there is any money to be saved over the long haul, or any weight to be shed, or any space to be recovered by going to lithium batteries. In my example, for instance, the lithium batteries were only 14lbs lighter than the GC's.

Certainly there are maintenance advantages, assuming a similar useful life span, but the last set of GCs I replaced were 10 years old and still working fine. Could you expect similar service life from the Lithiums?

[unyalli]

Originally Posted by Ramblin

Thanks.

So, this site has a 12V 40Ah battery for $200. To equal the capacity of a pair of 6V golf car batteries, you'd need 6 of them. 6 of them takes up double the space of a pair of golf car batteries, but weighs 14 lbs less. The lithium batteries have a 5 yr warranty but are only rated for 1750 charge/discharge cycles, which I presume would happen once every day under heavy dry camping use. The Lithium batteries cost $1200, whereas the golf car batteries are $300, not including the interconnect cables.

In this example, I fail to see the advantage of Lithium over lead/acid, even if cost were the same. What am I missing?

A set of GC2's from Sams Club is around $200 and provides 220ah. Have they figured out how to determine SOC with Lithium yet? Last I heard the biggest drawback with Lithium (outside astronomical cost) is you don't know when your about dead.

[hdossett]

Originally Posted by Ramblin

I used 2GC's as my example because it was easy. Larger systems just scale, right? So 4xGCs would be double the numbers. 6xGCs, triple, and so on.

Your example shows $1,200 for to replace 2 GCs. Mine shows $1,680 to replace 6. That's $600 vs. $280 per GC bat. Not exactly a linear scale!

GCs weigh in @ ~70 pounds, times six = 420 pounds!

LFP weigh in @ 30 times 4 for 120 pounds!

If you want to do this, you have to build your own to make it work, the same reason you buy GCs and not motorcycle batteries to build your bank, and also use it as a teaching moment!

As I said, I'm new to this and you must do your own math to get to where you want to go!

As far as determining SOC, battery monitors work pretty good for that. I used to have one until it went south, and it worked much better than resting voltage mainly because I did not have to wait for two hours to get a reading. And the ones on my cell phone and camera work pretty good too!


H

[Ramblin]

Originally Posted by hdossett

Your example shows $1,200 for to replace 2 GCs. Mine shows $1,680 to replace 6. That's $600 vs. $280 per GC bat. Not exactly a linear scale!

I used the 12V 40Ah battery from the link you provided to build a battery bank with equal Ah capacity to 2 GCs. You then said ' If you can get by with 2GCs...' . I was merely pointing out that you could take my numbers and multiply by three to get to your larger bank.

Your point about 'usable' amps is well taken though, so I'd need less capacity in the lithium bank to make a comparable bank.

The weights used also came from the site you linked for the 12V 40Ah battery I used in my analysis. For THAT battery, building a bank with the same AH rating as the GC batteries, the weight savings is but 14 lbs. per pair of GC's.

Originally Posted by hdossett

GCs weigh in @ ~70 pounds, times six = 420 pounds!

LFP weigh in @ 30 times 4 for 120 pounds!

If you want to do this, you have to build your own to make it work, the same reason you buy GCs and not motorcycle batteries to build your bank, and also use it as a teaching moment!

As I said, I'm new to this and you must do your own math to get to where you want to go!

As far as determining SOC, battery monitors work pretty good for that. I used to have one until it went south, and it worked much better than resting voltage mainly because I did not have to wait for two hours to get a reading. And the ones on my cell phone and camera work pretty good too!


H

Thank you for indulging me in this exercise. I clearly have a lot to learn about alternatives to my good old GCs. I honestly had not thought of using lower voltage cells to maximize space/weight/cost benefits. I was just looking at 12V cells. Can you link to the 3V cells you are referring to?

[hdossett]

Originally Posted by Ramblin

...Can you link to the 3V cells you are referring to?

Sorry about that! It's on page 2, of the link I listed.

Balqon - Advanced Transportation Solution

I was using the 3.2V 400AH in my example.

Edit: Found on another forum

"they are Yellow TS that Winston took over. Winston changed to Black for their batteries."

*TS = ThunderSky Just be careful out there!

H

[jasright]

Lead acid batteries have serious voltage dop below 80% charged where lifepo4 lhave a voltage frop at 20%.they last about five times longer and charge a lot faster, in as little as twenty minutes in you have the wattage. With solar revharging they would stay topprf off with no memory effect like lead acid. Meaning you don't have to completely drain them before recharging.

[rbertalotto]

This is very interesting to me. I often wondered when a conversation about lithium ion batteries would be started. It is certainly the future and right around the corner.

[Gocoffeer]

hdossett....If I could afford the lithium batteries...they would be in my rig now. The weight and space savings are amazing....the amount of recharge is even better. The DEEP Cycle capability is second to none when compared to an acid filled battery. I think a full time boon docker with a big cash roll would be attracted to these.

[hdossett]

Originally Posted by Gocoffeer

hdossett....If I could afford the lithium batteries...they would be in my rig now...

Yea, me too! Just not on the road enough the justify them. If I ever get back on the road full time, I think I would look at them very seriously, and triple my solar count, and maybe mount some on the side so they could be raised and used as window awnings!

H